Construction and application of high-temperature and high-yield engineered strains of xylitol and ethanol at the same time

Abstract

The invention relates to building and application of engineered strains capable of producing xylitol and ethanol at a high temperature simultaneously with a high yield. Concretely, N376F mutant genes of saccharomyces cerevisiae galactose permease (hexose transporter protein of hexose for transporting galactose and glucose) (ScGAL2) are effectively expressed in heat-resistant yeast strains YZJ015 by a gene engineering transformation method; meanwhile, K.marxianus glycerol-3-phosphate dehydrogenase (KmGPD1) genes are removed to cut off a glycerol production branch, so that the obtained strains YZJ119 obtain good capability of efficiently co-utilizing and fermenting glucose and xylose to produce the ethanol and the xylitol at a high temperature (higher than 42 DEG C). Under the condition of 42 DEG C, the YZJ119 can simultaneously use 43.95g / l of xylose and 83.11g / l of glucose to produce 40.43g / l of xylitol and 34.66g / l of ethanol in 28 hours; the production speed of the xylitol is 1.44g / l / h; the production speed of the ethanol is 1.24g / l / h; the yield of the xylitol is 0.92g / g; and the yield of the ethanol is 0.42g / g.

Description

technical field [0001] The invention relates to the field of biotechnology, in particular, constructs heat-resistant engineering yeast that can simultaneously use glucose and xylose to co-ferment to produce ethanol and xylitol at a relatively high temperature, and the production rate is greatly improved. It relates to the field of improving co-fermentation of glucose and xylose to produce ethanol and xylitol through engineering bacteria transformation. Background technique [0002] Xylitol is a five-carbon polyol and a normal intermediate product of xylose metabolism (Vandeska et al., 1996). Its properties determine that it has important application value in food and medicine. First of all, in the food industry, the sweetness of xylitol is comparable to that of sucrose, and it can be used as a sweetener. Utilized by bacteria, it can therefore prevent dental caries and can be used as an additive in anti-cavity foods for children (Dominguez et al., 1997). In addition, since ...

AI Technical Summary

Problems solved by technology

Glucose and xylose are the two main monosaccharide components of its hydrolyzate. To establish an economical industrial utilization process, efficient utilization and fermentation of the two sugars are required (Ha et al., 2011), but the current methods are not efficient enough , especially when glucose and xylose exist at the same time, due to the glucose inhibition effect, the ability of microorganisms to utilize xylose is often inhibited by glucose, resulting in low efficiency

The construction of various engineering strains has continuously improved the ability to use xylose to ferment xylitol, but the inhibitory effect of glucose is often difficult to remove

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